. The ammonite zonal sequence and ammonite Ot taxonomy in the Douvilleiceras mammillatum * 4 Superzone (Lower Albian) in Europe | c?mH^i^ui?lmY H. G. Owen Department of Palaeontology, British Museum (Natural History), Cromwell Road, London SW7 5BD, U.K. Contents Synopsis 178 Introduction 178 Current zonal and subzonal schemes 179 Casey 1961 179 Stratigraphic basis of the scheme 179 Destombes 1973, 1979 181 Stratigraphic basis of the scheme 184 Amedro 1980 190 Savel'ev 1973, 1974 191 The Subzone of 'HopHtes (Isohoplites) eodentatus" 195 Proposed new zonal and subzonal scheme , 197 .." The Superzone of Douvilleiceras mammillatum •. .i 197 The Zone of Sonneratia chalensis ' 198 Subzone of Sonneratia (Globosonneratia) perinflata 198 Subzone of Sonneratia (Sonneratia) kitchini 201 Subzone of Cleoniceras (Cleoniceras) floridum 201 The Zone of Otohoplites auritiformis 202 Subzone of Otohoplites raulinianus 204 Subzone of Protohoplites (Hemisonneratia) puzosianus 204 Subzone of Otohoplites bulliensis 206 Subzone of Pseudosonneratia (Isohoplites) steinmanni 206 Systematic Palaeontology 207 Stratigraphical distribution of the ammonite fauna 207 Systematic Notes 211 Family Douvilleiceratidae Parona & Bonarelli 211 Subfamily Douvilleiceratinae sensu stricto 211 Genus Douvilleiceras de Grossouvre 211 Family Cleoniceratidae Whitehouse 212 Subfamily Vnigriceratinae Savel'ev 214 Subfamily Cleoniceratinae Whitehouse 215 Genus Cleoniceras Parona & Bonarelli 216 Subfamily Lemuroceratinae nov 216 Family Hoplitidae Douville (Boehm) 217 Subfamily Sonneratiinae Destombes, Juignet & Rioult 217 Genus Sonneratia Bayle 219 Subgenus Globosonneratia Savel'ev 219 Subgenus Sonneratia sensu stricto 219 Genus Pseudosonneratia Spath 219 Genus Otohoplites Steinmann 222 Genus Anahoplitoides Casey 223 Subfamily Gastroplitinae Wright 223 Family Lyelliceratidae Spath 224 Subfamily Lyelliceratinae Spath 224 Family Mojsisovicsiidae Hyatt 225 Family Brancoceratidae Spath 225 Acknowledgements 226 References 226 Index 229 Bull. Br. Mus. nat. Hist. (Geol.) 44 (3): 177-231 Issued 29 September 1988 178 H. G. OWEN Synopsis The Lower Albian Substage is divided into an earlier Zone of Leymeriella tardefurcata and a later Zone of Douvilleiceras mammillatum the biostratigraphy of which is the subject of the present paper. Although the epicontinental seas of Europe encompassed a single ammonite faunal province during the mammilla- tum Zone, sedimentary sequences are scattered and incomplete in their subzonal representation. As a consequence, different zonal and subzonal schemes have been devised for the relatively well known and well developed sequences in England, France, and the Soviet Union. Four such schemes are in current use, all reflecting the degree of representation in the particular region concerned. Because of this variation in the degree of representation in the mammillatum Zone lithological sequences, disagreement has arisen between French and English workers on the status and position of the Subzones of Otohoplites raulinianus and Protohoplites (Hemisonneratia) puzosianus. This disagreement has important implications both from the stratigraphic point of view and for the ammonite systematics. Sufiicient information is available to settle this problem and to correlate the zonal and subzonal schemes currently in use in the Soviet Union with that of western Europe. A revised zonal and subzonal scheme is established in this paper which can be applied to the whole of the European province in the later part of the Lower Albian; the rank of the Zone of Douvilleiceras mammillatum being raised to that of a Superzone with global application during this period of time. A review of the ammonite fauna is made. On the basis of new evidence, the Cleoniceratidae is redefined as a family with three subfamilies, the Vnigriceratinae, the nominate subfamily Cleoniceratinae, and the Lemuroceratinae nov. The Hoplitidae is considered to consist of three subfamilies, the Hoplitinae sensu stricto, the Sonneratiinae, and with some question the Gastroplitinae. A number of species of individual genera, described separately from western and eastern Europe, are considered to be conspecific. Introduction Lower Albian sediments in Europe are very scattered in occurrence, frequently condensed and incomplete in their representation of the subzonal sequence, and there is much evidence of periods of strong current-scour activity reflecting relatively shallow epicontinental seas in which tectonic movements were manifest. Only in relatively deep basins are thick and more contin- uous sedimentary sequences preserved. Elsewhere, the periods of submarine current-scour reduced previous episodes of sedimentation to remnants, or to phosphatic pebble horizons which may, in turn, have been reworked more than once. This latter feature of polyphase erosion has produced difficulties in the determination of the ammonite subzonal sequence, and even of the zonal sequence, when mixtures of disinterred Leymeriella tardefurcata Zone and Douvilleiceras mammillatum Superzone pebble faunas have occurred. This is well illustrated by the condensed phosphatic pebble bed sequences in the northern alpine zone extending from the Alpes Maritimes (France) eastwards through Switzerland, Austria and southern Germany. Even in the relatively deep basinal areas such as the Harz foredeep region in the tardefurcata Zone and the central Aube and northern Pays de Bray in the mammillatum Superzone, non- sequences or periods of strong current-induced condensation are to be found. There is borehole evidence of a relatively thick development of clays of later mammillatum Superzone age in the Harz foredeep in the Hannover-Braunschweig area of north Germany, a development which might also be present in the Polish Trough. Elsewhere at outcrop in north Germany and Poland, strong current scour has condensed or removed altogether sediments of this Superzone. In the case of the Douvilleiceras mammillatum Superzone, these episodes of non-sequence and erosional condensation have led to a disagreement in western Europe concerning the sequence of Subzones and the zonal scheme. Furthermore, in the Soviet Union, thick mammillatum Superzone sequences are present in the Mangyschlak Peninsula, Transcaspia, in which a differ- ent zonal scheme from that of western Europe has been recognized, albeit that the ammonite faunas are closely comparable. Although parts of the sequence are better developed than in contemporaneous sediments in western Europe, non-sequences are apparent also in Mangysch- lak. Nonetheless, the ammonites figured so far permit a direct correlation of the Russian zonal scheme with that of England and France. The intention of this paper is to discuss the evidence of ammonite faunal succession within the mammillatum Superzone in Europe in order to stabilize a zonal and subzonal scheme which AMMONITE ZONAL SEQUENCE AND TAXONOMY IN THE D. MAMMILLATUM SUPERZONE 179 can be applied throughout the whole of this ammonite faunal province. Although the ammon- ite fauna contains elements which are more geographically widespread than the epicontinental seas of Europe, such as Douvilleiceras, Beudanticeras, Cleoniceras, Tegoceras, Oxytropidoceras, Protanisoceras, Rossalites and Hamites, ammonites such as Sonneratia and Pseudosonneratia, together with their offshoots Otohoplites, Protohoplites, Tetrahoplites etc., are restricted to the European shelf seas. In this respect, the distribution of this latter restricted group of ammonites within the mammillatum Superzone European faunal province presages the hoplitinid faunal province recognized in the Middle and Upper Albian, and which continues into the Cenomanian. Current zonal and subzonal schemes Prior to 1984, two fundamentally different zonal and subzonal schemes were in use for western European mammillatum Superzone sequences. The first of these schemes was erected by Casey (1961) and has been used throughout his important monograph of the Lower Greensand Ammonoidea (Casey I960-) and by other workers in the United Kingdom. The second scheme was devised by Destombes (1973, 1979) based upon sequences exposed in northern France. A variation of this latter scheme has been proposed by Amedro (1980, 1981, 1984a, b). In the Soviet Union, Savel'ev (1973a, b, 1974) has made a detailed study of the Lower Albian sequence in the Mangyschlak Peninsula, Transcaspia. Based on this sequence, he has erected an apparently distinct zonal and subzonal scheme from that recognized in the mammillatum Super- zone of western Europe. However, his Subzones can be correlated directly with those of western Europe because most of the distinctive species are present in the sequences at both extremities of the European province. These different schemes are discussed now in greater detail. Casey (1961) Careful bed by bed collecting in the Gault-Lower Greensand Junction Beds in southern England and East Anglia allowed Casey (1961) to revise the ammonite subzonal sequence of the Douvilleiceras mammillatum Zone of earlier workers such as Spath (1923-43). He divided the Zone into four Subzones as shown in Table 1. Stratigraphic basis of the scheme The lithological representation of the mammillatum Zone in southern England and in East Anglia was recognized as being marked by episodes of current induced condensation and non-sequence which involved different time intervals at different places. No single section has yet revealed a continuous and relatively complete lithological succession in which the full sequence of ammonites can be